Communication technologies that link electronic devices in a networked fashion are well known. Examples of communication networks include wired packet data networks, wireless packet data networks, wired telephone networks, wireless telephone networks, and satellite communication networks, among other networks. These communication networks typically include a network infrastructure that services a plurality of client devices. The Public Switched Telephone Network (PSTN) is probably the best-known communication network that has been in existence for many years. The Internet is another well-known example of a communication network that has also been in existence for a number of years. These communication networks enable client devices to communicate with one another other on a global basis. Wired Local Area Networks (wired LANs), e.g., Ethernets, are also quite common and support communications between networked computers and other devices within a serviced area. Wired LANs also often link serviced devices to Wide Area Networks and the Internet. Each of these networks is generally considered a “wired” network, even though some of these networks, e.g., the PSTN, may include some transmission paths that are serviced by wireless links.
Wireless networks have been in existence for a relatively shorter period. Cellular telephone networks, wireless LANs (WLANs), and satellite communication networks, among others, are examples of wireless networks. Relatively common forms of WLANs are IEEE 802.11(a) networks, IEEE 802.11(b) networks, and IEEE 802.11(g) networks, referred to jointly as “IEEE 802.11 networks.” In a typical IEEE 802.11 network, a wired backbone couples to a plurality of Wireless Access Points (APs), each of which supports wireless communications with computers and other wireless terminals that include compatible wireless interfaces within a serviced area. The wired backbone couples the APs of the IEEE 802.11 network to other networks, both wired and wireless, and allows serviced wireless terminals to communicate with devices external to the IEEE 802.11 network. Devices that operate consistently with an IEEE 802.11 protocol also typically support ad-hoc networking in which wireless terminals communicates directly to one another without the presence of an AP.
WLANs provide significant advantages when servicing portable devices such as portable computers, portable data terminals, and other devices that are not typically stationary and able to access a wired LAN connection. However, the data rates provided by IEEE 802.11(b) networks are less than those data rates provided by even older wired LANs. Thus, in order to provide greater data rates, WLANs are often upgraded to newer available technologies, e.g., IEEE 802.11(g). WLANs that are upgraded to meet the IEEE 802.11(g) standard typically must also support legacy IEEE 802.11(b) devices in the shared 2.4 GHz ISM band.
Problems exist when supporting legacy devices. One particular problem relates to the differing slot times supported by the IEEE 802.11(b) and the IEEE 802.11(g) devices. IEEE 802.11(g) devices, which use a 9 μs slot time, have an advantage over IEEE 802.11(b) devices, which use a longer 20 μs slot time, when accessing a shared channel. Such is the case because in the Carrier Sense Multiple Access (CSMA) with Collision Detection and Random Backoff operations employed by both IEEE 802.11(b) and IEEE 802.11(g) devices, the IEEE 802.11(g) devices will attempt to access the shared channel sooner after a collision than will the IEEE 802.11(b) devices. Thus, the IEEE 802.11(g) devices will have an unfair advantage in accessing the shared channel.
Thus, there is a need in the art for operations that will allow legacy devices and next generation devices to share channels in a service area supported by a WLAN in a fair and equitable manner.